A micromethod was developed which can detect subnanogram quantities of fluoride in microliter samples using conventional equipment and reagents. Results using this method were reproducible when used to determine fluoride concentrations in the range of 0.02 to 100 ppm F; a modification of the method extended the sensitivity to 0.004 ppb. Fluoride levels in submilligram quantities of dental plaque and submilliliter volumes of blood from individuals participating in clinical trials were effectively determined using this method. (Z01 DE 00263 01 CPR)